JP4458793B2 - Belt tension control method for belt-type continuously variable transmission with tensioner - Google Patents

Description

  The present invention relates to a belt tension control method for a belt type continuously variable transmission mounted on a vehicle such as an automobile.

Conventionally, a drive pulley and a driven pulley, a V-belt wound around both pulleys, and a starting clutch for intermittently rotating the engine to the drive pulley, the belt winding diameter of the drive pulley and the driven pulley A belt-type continuously variable transmission (hereinafter referred to as CVT) that changes engine speed and outputs engine speed is known. In such a CVT, tension control for applying an appropriate tension to the V-belt is performed in order to prevent slippage of the V-belt. As such tension control of the V-belt, for example, as disclosed in Patent Document 1, a V-belt is wound between a driving pulley having a hydraulic servo and a driven pulley having a hydraulic servo, and the line pressure is set. Supplying the hydraulic servo of one of the pulleys to generate a clamping force that becomes the belt tension, and changing the gear ratio by supplying the transmission hydraulic pressure with the line pressure adjusted to the hydraulic servo of the other pulley Something to do is proposed.
JP-A-5-141515

  By the way, in such a belt-type continuously variable transmission, what is provided with the starting clutch comprised by an electromagnetic clutch etc. in order to smooth the torque transmission at the time of start is known. In such a case, when the starting clutch rotates synchronously, the tension of the V belt is controlled based on the engine torque, and when the starting clutch rotates asynchronously, the transmission torque of the starting clutch is set. Based on this, the tension of the V-belt is controlled. With such a configuration, for example, when shifting from a driving state in which the starting clutch rotates asynchronously to a synchronized driving state, such as when the accelerator is turned off after the vehicle starts, based on the transmission torque of the starting clutch. From the state in which the tension of the V-belt is controlled, the operation state in which the starting clutch is synchronized is changed, so that the necessary tension of the V-belt increases, but when the starting clutch is synchronized, the tension control of the V-belt based on the transmission torque is performed. As a result, there was a shortage. As a result, the V-belt slips and accurate shift control may not be performed.

  The object of the present invention is to eliminate such problems.

In other words, the belt tension control method for a belt-type continuously variable transmission including a tensioner according to the present invention is such that a belt is passed between a driving pulley and a driven pulley whose belt winding diameter can be changed, and a power interrupting clutch is connected to a driving side. Applicable to a belt type continuously variable transmission interposed between a pulley and an engine or between a driven pulley and a differential device. When the power interrupting clutch rotates synchronously, the tensioner is based on the engine torque. The belt tension control of the belt type continuously variable transmission having a tensioner that controls the belt tension based on the transmission torque of the power interrupting clutch when the power interrupting clutch rotates asynchronously. If it is anticipated that the power interrupting clutch will transition from an asynchronous state to a synchronous state, the engine torque and Of the transmission torque of the force intermittent clutch, and controlling the tension of the belt by the tensioner so that the tension is set based on the torque of the person who needs the belt tension is increased.

According to such a configuration, in an operation state in which the power interrupting clutch is assumed to transition from the asynchronous state to the synchronous state, the engine torque and the transmission torque of the power interrupting clutch are based on the larger torque. Since the tension of the belt is controlled by the tensioner so as to be the set tension, it is possible to prevent the belt tension from becoming insufficient even if the power interrupting clutch is subsequently brought into a synchronized state. For this reason, it is possible to prevent a problem that the belt is slack and the driving force from the driving pulley to the driven pulley is insufficient.

  As described above, the present invention is based on the large torque of the engine torque and the transmission torque of the power interrupting clutch when the power interrupting clutch is expected to transition from the asynchronous state to the synchronous state. Since the belt tension is controlled so that the tension is set, the belt tension can be increased in advance when the required belt tension rises suddenly when the polarity of the transmission torque is reversed. Can be prevented.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

  As shown in FIG. 1, the continuously variable transmission 100 according to this embodiment includes a starting clutch unit 1, a continuously variable transmission 2, a switching unit 3, and a differential device 4.

  The starting clutch unit 1 includes a starting clutch 13 that is a power interrupting clutch that connects and disconnects the switching unit 3 and the driven shaft 23. The starting clutch 13 is called a wet multi-plate type, and connection to the driven shaft 23 and disconnection from the driven shaft 23 are controlled by applied clutch hydraulic pressure.

  The continuously variable transmission 2 includes a drive pulley 22 provided on the drive shaft 21, a driven pulley 24 provided on the driven shaft 23, and a V belt 25 wound around the drive pulley 22 and the driven pulley 24. The input side rotational speed detection device 6 and the output side rotational speed detection device 7 for detecting the rotational speeds of the driving pulley 22 and the driven pulley 24, and a tensioner for applying tension to the V belt 25 (see FIG. 2). 5). The tensioner 5 is disposed between the driving pulley 22 and the driven pulley 24 and is in contact with the V belt 25. The tension arm 52a and the tension arm 52a are pressing mechanisms 52 that press the roller 51 against the V belt 25. A control actuator 52b for controlling the pressing force of the belt, and the tension arm 52 is controlled by the control actuator 52b to apply a pressing force to the V-belt 25 so that the belt tension described later is obtained. .

  The driving pulley 22 has a fixed sheave 22a and a movable sheave 22b. Pulse signal teeth 61 constituting the input-side rotational speed detection device 6 are provided at a predetermined pitch on the circumference of the fixed sheave 22a. It is. On the other hand, behind the movable sheave 22b, an operating device (not shown) such as a hydraulic pump, a hydraulic oil pipe, or the like is provided. Similarly, in the driven pulley 24, pulse signal teeth 71 constituting the output-side rotational speed detection device 7 are provided at a predetermined pitch on the circumference of the fixed sheave 24a, and the movable sheave 24b The actuator is configured to move in synchronism with the movable sheave 22b of the driving pulley 22. The driving pulley 22 and the driven pulley 24 are configured such that the belt winding diameter can be changed by moving the movable sheaves 22b and 24b. The input side rotational speed detection device 6 and the output side rotational speed detection device 7 include pickups 62 and 72 provided at positions facing the pulse signal teeth 61 and 71, respectively. It is electrically connected to an electronic control device 8 to be described later.

  The switching unit 3 includes a forward gear 31 and a reverse gear 32 that are rotatably supported by the driven shaft 23, and one of the forward gear 31 and the reverse gear 32 is a clutch output shaft by a dog clutch (not shown). 14 is connected. And it is comprised so that motive power may be transmitted to the differential apparatus 4 via the idler gears 33a and 33b with respect to such a switching part 3. FIG.

  Such a continuously variable transmission 2 is controlled by an electronic control unit 8. The electronic control device 8 includes a central processing unit 81, a storage device 82, an input interface 83, and an output interface 84, and is mainly composed of a microcomputer system. The input interface 83 includes an input side rotational speed signal Pi (hereinafter referred to as an input side pulse signal) Pi output from the pickups 62 and 72 of the input side rotational speed detection device 6 and the output side rotational speed detection device 7 and an output. A side rotation speed signal (hereinafter referred to as an output side pulse signal) Po is input, a vehicle speed signal output from a vehicle speed sensor for detecting the vehicle speed, and an engine water temperature, a throttle opening degree, an engine from an engine control device (not shown) Various signals such as the rotational speed and engine torque are input.

The electronic control unit 8 controls the tension of the V-belt 25 based on the engine torque Teg when the start clutch 13 is rotating synchronously, and the start clutch when the start clutch 13 is rotating asynchronously. 13, the tension of the V-belt 25 is controlled based on the transmission torque Tc of the engine 13. When the start clutch 13 is expected to transition from the asynchronous state to the synchronous state, the engine torque Teg and the transfer torque of the start clutch 13 are controlled. The tensioner includes a belt tension control program for controlling the tension of the V-belt 25 from 5 so that the tension is set based on a large torque with Tc.

  The belt tension control program is executed based on the schematic procedure shown in FIG.

First, in step S1, it is determined whether or not the starting clutch 13 is synchronized. In this determination, the driven pulley angular speed ωi and the output side angular speed ωo of the starting clutch 13 are compared, and when both are substantially equal, it is determined that they are synchronized. If it is determined that the start clutch 13 is synchronized, the engine torque Teg is calculated by the following equation in step S2, and the necessary belt tension based on the calculated engine torque is calculated. In the following equation, Te is an estimated engine torque value calculated based on the intake pressure and the rotational speed of the engine, Ie is an inertia in an input portion including a part of the engine and the continuously variable transmission 100, and ωe is an engine angular velocity. , GR is a reduction ratio.
Teg = {Te−Ie * (dωe / dt)} * GR (1)

  The necessary belt tension is set to a value exceeding the minimum belt tension necessary for preventing belt slippage when the start clutch 13 is synchronized with the selected torque. FIG. 4 shows the relationship between torque and necessary belt tension in this case. As shown in the figure, when the continuously variable transmission 2 is driven by the engine, the necessary belt tension tends to increase slowly with respect to the increase in torque. When driven, it increases rapidly with increasing torque.

  On the other hand, if it is determined in step S1 that it is asynchronous, it is determined in step S3 whether or not the difference between the driven pulley angular velocity ωi and the output side angular velocity ωo is large. This determination is to determine whether the state is completely asynchronous or has a possibility of transition to the synchronous state, and is different when the difference between the driven pulley angular velocity ωi and the output side angular velocity ωo is, for example, 150 rpm. Is determined to be large. In this case, the magnitude of the driven pulley angular velocity ωi and the output angular velocity ωo are not compared, but the amount of change in the difference between the driven pulley rotational speed and the output clutch rotational speed of the starting clutch 13 is combined with the comparison result. It may be a thing.

If it is determined in step S3 that the difference is large, the belt tension based on the transmission torque of the starting clutch 13 is calculated in step S4. The transmission torque Tc is calculated by the following formula. In the following equation, P is the clutch hydraulic pressure, A is the piston area where the clutch pressure is applied to the clutch, f is the elastic force of the return spring, N is the number of friction surfaces of the starting clutch, μ is the dynamic friction coefficient, and R is the effective radius. It is.
Tc = (P * A−f) * N * μ * R (2)
However, when ωi >> ωo, the positive transmission torque Tc
When ωi << ωo, negative transmission torque Tc

  If the difference between the driven pulley angular velocity ωi and the output side angular velocity ωo is small in step S3 (when there is a possibility of transition to a synchronous state), the driven pulley angular velocity ωi exceeds the output side angular velocity ωo in step S5. It is determined whether or not. When it is determined that the driven pulley angular velocity ωi exceeds the output side angular velocity ωo, the required belt tension based on the engine torque Teg is compared with the required belt tension based on the transmission torque Tc of the start clutch 13 in step S6. Use the higher required belt tension.

  On the other hand, if it is determined in step S5 that the driven pulley angular velocity ωi is lower than the output side angular velocity ωo, the necessary belt tension based on the engine torque Teg and the negative transmission torque of the start clutch 13 are determined in step S7. The required belt tension based on Tc is compared to obtain the higher required belt tension. In this case, the polarity of the transmission torque Tc is determined by the slip direction of the start clutch 13, in other words, the difference between the rotation speed of the driven shaft 23 and the rotation speed on the output side of the start clutch 13. Specifically, when the rotational speed on the output side of the starting clutch 13 exceeds the rotational speed of the driven shaft 23, the polarity is determined to be negative by the difference in the rotational speed.

Thereafter, in step S8, the belt tension of the V belt 25 is controlled by the tensioner 5 so that the calculated required belt tension is obtained.

  In such a configuration, for example, at the time of starting, when the starting clutch 13 is expected to transition from the asynchronous state to the synchronous state, in other words, it is in the asynchronous state and approaches the reference for determining the synchronous state. In the state, step S1, step S3, step S5, step S6 and step S8, or step S1, step S3, step S5, step S7 and step S8 are executed in order to control the belt tension of the V belt 25. .

  Therefore, even when the required belt tension rapidly increases due to synchronization of the start clutch 13, the belt tension can be increased in advance, so that the state where the V-belt 25 does not slip can be continued.

  On the other hand, if it is determined in step S1 that the starting clutch 13 is synchronized, steps S2 and S8 are executed in order, and the set belt tension is calculated based on the engine torque Teg. Therefore, the set belt tension can be accurately set based on the torque in anticipation of the rotational fluctuation, and the slip of the V belt 25 can be prevented.

  When the starting clutch 13 is synchronized, the engine torque Teg is negative and the rotational speed of the driving pulley 22 decreases, so that only the engine torque, that is, the inertia Ie in the equation (1), is obtained. The belt tension may be controlled so as to be based on the engine torque calculated in the equation having no term and not considering the inertia Ie.

In FIG. 5, first, in step S <b> 11, it is determined whether the start clutch 13 is synchronized as in the above embodiment. When the synchronization of the starting clutch 13 is determined, in step S12, the engine torque Teg calculated in consideration of the inertia is compared with the basic engine torque Tegx calculated without considering the inertia, and a large torque is determined. To do. The basic engine torque Tegx is calculated by the following equation.
Tegx = Te * GR (3)

  On the other hand, if it is determined in step S11 that it is asynchronous, step S13 is executed. Step S14, step S15, step S16 and step S17 following step S13 and step S13 have the same contents as the above-described step S3, step S4, step S5, step S6 and step S7, and will not be described.

  In such a configuration, for example, when a speed reduction operation is performed and the gear ratio is changed according to the vehicle speed during that time, that is, the engine torque is negative, and the speed change state in which the rotational speed of the driving pulley 22 decreases. When the change of the gear ratio is completed, the necessary belt tension of the V belt 25 may increase rapidly. In the case where the tension of the V-belt 25 is controlled by the tensioner 5, when the continuously variable transmission 2 is rotated by the engine torque from the rotationally driven state by the torque from the axle, FIG. As shown, the required belt tension varies greatly. In such a case, the basic engine torque Tegx that does not take into account the inertia shown in the above equation (3) is smaller by an amount based on the inertia of the engine torque Teg that takes into account the inertia shown in the above equation (1). Therefore, in the above-described shift state, the necessary belt tension is calculated based on the basic engine torque Tegx.

    Therefore, when such a change occurs, the possibility that the V-belt 25 slips increases. However, by configuring as described above, the belt tension of the V-belt 25 can be controlled by setting the belt tension high. It is possible to prevent the V belt 25 from slipping.

  The present invention is not limited to the above embodiment.

  In the above embodiment, the start clutch 13 is interposed between the driven pulley 24 and the differential device 4. However, the start clutch 13 may be interposed between the engine and the drive pulley 22.

  In the above embodiment, when the starting clutch 13 is synchronized, the engine angular acceleration dωe / dt is not an observed value but a shift speed in the above formula (1), formula (3), or formula (1). Of the belt tensions calculated based on the respective engine torques calculated by changing the target values to those calculated from the target value, the maximum belt tension may be adopted. In this way, the belt tension can be set in feedforward control by using the target value of the shift speed instead of the observed value of the engine angular acceleration dωe / dt. Even in an operating state where the vehicle suddenly rises, slipping of the V-belt 25 can be prevented.

  In addition, the specific configuration of each part is not limited to the above embodiment, and various modifications can be made without departing from the spirit of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS Structure explanatory drawing which shows schematic structure of embodiment of this invention. The schematic diagram which shows the structure of the tensioner of the embodiment. The flowchart which shows the outline of the control procedure of the embodiment. The graph which shows the relationship between the torque of the same embodiment, and belt tension. The flowchart which shows the outline of the control procedure of other embodiment of this invention.

Explanation of symbols

2 ... continuously variable transmission 4 ... differential device 13 ... starting clutch 22 ... driving pulley 24 ... driven pulley 25 ... V belt 8 ... electronic control device 81 ... central processing unit 82 ... storage device 83 ... input interface 84 ... output interface

Claims (1)

A belt in which a belt is stretched between a driving pulley and a driven pulley whose belt winding diameter can be changed, and a power interrupting clutch is interposed between the driving pulley and the engine or between the driven pulley and the differential device. When the power intermittent clutch rotates synchronously, the belt tension is controlled by the tensioner based on the engine torque, and the power intermittent clutch rotates asynchronously. In a belt tension control method for a belt-type continuously variable transmission including a tensioner that controls tension of a belt based on transmission torque of a power interrupting clutch,
If the power interrupting clutch is expected to transition from the asynchronous state to the synchronous state, it is set based on the torque that increases the required belt tension between the engine torque and the transmission torque of the power interrupting clutch. A belt tension control method for a belt-type continuously variable transmission equipped with a tensioner, wherein the tension of the belt is controlled by a tensioner so that the tension becomes constant .

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